Preparation of viscous polymers



PREPARATXON OF VISCOUS POLYMERS Sterling E. Voltz, Brookhaven, Pa., assignor to Sun Oil fompany, Philadelphia, Pa., a corporation of New ersey No Drawing. Filed Apr. 6, 1959, Ser. No. 804,112

6 Claims. (Cl. 260683.15)

This invention relates to the preparation of viscous polymers and more particularly concerns a process for polymerizing alpha-monoolefin hydrocarbons having three or more carbon atoms per molecule to form viscous oily polymers which have utility as additives for other oils or as lubricants per se.

In the polymerization of alpha-monoolefins which have three or more carbon atoms per molecule, those in which there is a substituent at the beta position generally are more easily polymerized than straight chain monoolefins or than those which have one or more substituents located other than at the beta position. The present invention is directed to the catalytic polymerization of the more difiicultly polymerizable alpha-monoolefins, i.e. those which do not have a substituent at the beta position, for the purpose of producing viscous oily products.

According to the invention, alpha-monoolefins having the formula H H RC=CH wherein R is an alkyl radical having 1-8 carbon atoms, are polymerized by contacting with a dispersion formed by adding titanium dihydride, a mercuric halide and an aluminum trialkyl to an inert organic liquid medium. It has now been found that such dispersions are highly effective catalytic systems for polymerizing the specified monoolefins, or mixtures thereof, to viscous oily products In preparing the catalyst system of the present invention titanium dihydride and a mercuric halide, such as HgC1 HgF HgBr or Hgl both in finely divided anhydrous form, are dispersed in an organic liquid reaction medium and an aluminum trialkyl, e.g. aluminum triethyl, is added. The catalytic components can be introduced to the liquid reaction medium in any order of addition. Any organic liquid which will be inert under the reaction conditions can be used. Preferably, hydrocarbon liquids are employed, for example, hexanes, heptanes, octanes, cyclopentanes, cyclohexanes, benzene, toluene, xylenes, decalin and the like. Nonterminal olefins which will not react under the conditions employed during the reaction can also be used.

The aluminum compound employed in the foregoing catalyst system can be any aluminum trialkyl wherein the alkyl groups each have 1-10 carbon atoms. The preferred trialkyl is aluminum triethyl; however, other trialkyls such as the trimethyl triisobutyl, triisoctyl and tridecyl compounds of aluminum can be used with good results.

The polymerization reaction is carried out by contacting the above-described catalyst system with the monomeric olefin which can be introduced into the reaction vessel in either vapor or liquid form. The temperature of the system generally should be above C. and may be as high as 150 C. or even higher. As a general rule the rate of polymerization increases as the reaction temperature is increased. The reaction can be conducted under atmospheric pressure if the boiling point of the reaction medium is above the reaction temperature em- 2,965,692 Patented Dec. 20, 1960 ployed, or an elevated pressure can be employed when the reaction temperature is above the normal boiling point of the reaction medium. If the monomeric olefin charge is a normally gaseous olefin such as propylene, it is advantageous to maintain an elevated pressurein the reactor since this increases the concentration of dissolved olefin in the reaction mixture and results in an increase in reaction rate. During the course of the reaction it is desirable to stir the reaction mixture continuously in order to elfect efiicient contact betweenthe reactant and thecatalyst particles.

In preparing the reaction mixture the proportions-of components can be varied widely, and the rate of reaction will depend to an extent on the proportions selected. As a general rule, it is desirable to use a volume ratio of the charge olefin to reaction medium in the range of 0.2 to 5 on a liquid basis. It is also desirable that the molar ratio of both the TiH and the mercuric halide to the charge olefin be in the range of 0.0001 to 0.05 and more preferably 0.001 to 0.01, and that the molar ratio of the aluminum trialkyl to the Til-I be in the range of 0.1 to 10 and more preferably 0.2 to 5. The reaction temperature selected will depend to an extent upon the particular olefin to be polymerized but generally will be in the range of 0 to 150 C. and more preferably 50 to C.

The above-described procedure results in the formation of viscous oily polymers which remain dissolved in the reaction medium depending upon the reaction conditions and the particular monomer used. Upon completing the reaction a polar compound such as methanol is added to the reaction mixture to deactivate the catalyst system. The oily polymer product can be separated from the catalyst and reaction medium by filtration, extraction and/or distillation. The resulting product can be utilized as a lubricant or can be used to thicken other oils and improve viscosity index. It can also be blended with other materials, for example, petroleum Wax, to impart desirable characteristics. The products of the invention can. if desired, be hydrogenated before final use in order to eliminate terminal unsaturation.

The following examples illustrates the invention more specifically:

Example An inert reaction medium consisting of n-heptane was charged to a reaction vessel and finely divided anhydrous Til-i and I-IgCl each were added thereto in a molar proportion of one part to 100 parts of the hereinafter specified olefin monomer. Triethyl aluminum was then added to the mixture in a molar proportion to the Til-l of 3:1. The mixture was heated while being stirred until a temperature of 50 C. was reached. The charge olefin, 4- methylpentene-l, was then added in a volume amount equivalent to the n-heptane and the mixture was stirred for 24 hours with the temperature being maintained at about 50 C. Methanol was then added, the mixture was filtered to separate catalyst particles and the filtrate was distil ed to remove the n-heptane and methanol. A viscous oily product was obtained in a yield of roughly 30% by weight based on the 4-methylpentenel charged to the system.

A higher yield of viscous polymer product can be obtained by operating in the above manner but employing a higher reaction temperature, e.g. by employing a temperature of 100 C. while maintaining the system under pressure.

By way of comparison, when the above example is repeated except that either cupric chloride or ferric chloride is substituted for the mercuric chloride, no polymerization of the 4-methylpentcne-1 is obtained. Likewise, when the example is repeated except that ZrH is substituted for the TiHg,

3 only a small amount of liquid polymer results.

The polymerization of other alpha-olefins having 31O carbon atoms and which do not have any substituent 'in the beta position can be carried out in the manner above described with substantially similar results. For example, alpha-olefins such as propylene, butene-l, 3-methylbutene-l', 3-ethylbutene-l, pentene-l, hexene-l, 4-methylpentene-l, 3,4-dimethylpentene-1, octene-l, vinylcyclohexane, 4,4-dimethylpentene-l, decene-l and 5-ethyl-4,4-

dimethylhexene-l can be polymerized in accordance with the invention to yield viscous oily polymers.

- I claim:

1. Polymerization method for forming viscous polymers which comprises contacting, under polymerizing conditions including a temperature in the range of 0150 (3., an alpha-monoolefin having the formula 11 n R c-=01;

wherein R is an alkyl radical having 1-8 carbon atoms, with a catalyst system prepared by incorporating in an inert organic liquid medium TiH a mercuric halide and an aluminum trialkyl.

2. Method according to claim 1 wherein said halide is HgCl- 3. Method according to claim 2 wherein said aluminum trialkyl is aluminum triethyl.

4. Method according to claim 1 wherein the polymerizing conditions include a temperature in the range of -100 C. a

5. Method according to claim 4 wherein said alphamonoolefin is 4-methy1pentene-1.

6. Method according to claim 5 wherein said halide is HgCl and the aluminum trialkyl is aluminum triethyl.

References Cited in the file of this patent UNITED STATES PATENTS 2,886,561 Reynolds et al. May 12, 1959 2,891,044 Matlach June 16, 1959 FOREIGN PATENTS 1,139,806 France Feb. 18, 1957 1,157,382 France Dec. 30, 1957 

1. POLYMERIZATION METHOD FOR FORMING VISCOUS POLYMERS WHICH COMPRISES CONTACTING, UNDER POLYMERIZING CONDITIONS INCLUDING A TEMPERATURE IN THE RANGE OF 0-150*C., AN ALPHA-MONOOLEFIN HAVING THE FORMULA 